RGB illuminator with calibration via single detector servo

• US 6,633,301 B1
• Filed: 05/17/1999
• Issued: 10/14/2003
• Est. Priority Date: 05/17/1999
• Status: Expired due to Fees

• Current Assignee: Citizen Finetech Miyota Company Limited (Citizen Electronics Company Limited)
• Original Assignee: DT FLCO, Inc. (Micron Technology, Inc.)
• Inventors: Donohue, Ryan Patrick, Malzbender, Rainer, Lysaght, Colm, Jusuf, Gani, Handschy, Mark A., Dallas, James M.
• Primary Examiner(s): Razavi, Michael
• Assistant Examiner(s): Havan, Thu Thao
• Application Number:
  US09/313,227
• Time in Patent Office: 1,611 Days
• Field of Search: 345/147, 345/432, 345/83, 345/82, 345/84, 345/85, 345/89, 345/597, 345/598, 345/599, 345/600, 345/603, 345/604, 345/605, 345/88, 345/690-699, 348/68, 348/745, 348/70, 348/181, 348/71, 348/180, 348/744, 348/189, 362/29, 362/30, 362/555, 362/558
• US Class Current: 345/597
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 5/02 characterised by the way in which colour is displayed details of colour display specific for CRTs G09G1/28; specific for flat matrix panels other than liquid crystal displays G09G3/2003; specific for liquid crystal displays G09G3/3607

Abstract

A display system includes a light modulator divided into an array of individually controllable pixels and an input-driven illumination device. The illumination device is adapted to receive a variable input and is configured to direct light of variable intensity onto the modulator, depending on the input. The display system further includes a calibrating arrangement for establishing the input to the illumination device to produce a desired intensity level of light. The calibrating arrangement includes a light sensing mechanism, which senses the light from the illumination device while the illumination device is driven by an initial input. The calibration arrangement is configured to determine a comparison between the sensed light and a value representative of the desired-intensity level. The calibration arrangement further includes a control arrangement responsive to the comparison for varying the input so as to provide light of the desired intensity level.

Claims

1. A display system comprising:

a spatial light modulator divided into an array of individually controllable pixels;

a separate input-driven illumination device selected from a group of similar illumination devices which are each adapted to receive a variable input and configured to direct light of variable intensity onto the modulator, depending on said input; and

an arrangement adapted for connection with the selected illumination device for providing to the selected illumination device a specific input for a desired intensity level of said light, said specific input being provided from predetermined calibration information that is particular to the selected illumination device, said arrangement including a memory device for storing said calibration information.

2. A display system according to claim 1, wherein said predetermined calibration information is stored in said memory device in binary form.

3. A display system according to claim 1, wherein said memory device is programmable read-only memory.

4. A display system according to claim 1, wherein the selected illumination device contains one, and only one, light source.

5. A display system according to claim 1, wherein the selected illumination device contains a plurality of light sources for producing light of different colors and wherein the predetermined calibration information includes a specific value for each light source wherefrom a specific input for each light source is generated so as to cause each light source to produce light of a particular intensity corresponding to its specific input whereby the light sources together produce combined light of a desired color.

6. A display system according to claim 5, wherein the desired color is white.

7. A display system according to claim 5, wherein the particular intensity of light produced by each light source is different.

8. A display system according to claim 5, wherein the illumination device consists of red, green and blue light-emitting diodes.

9. A display system comprising:

a light modulator divided into an array of individually controllable pixels;

a separate input-driven illumination device having one or more light sources which are adapted to receive variable inputs and which are configured to direct light of variable intensities onto the modulator, depending on said inputs; and

a calibrating arrangement for establishing the inputs for a desired intensity level of said light from each light source, the arrangement including a light sensing mechanism which senses said light from one light source at a time while each light source is driven by an initial input, the calibration arrangement being configured to determine a comparison between the sensed light and a value representative of the desired intensity level of light from the light source, the calibration arrangement further including means responsive to the comparisons for varying the inputs so as to provide light of said desired intensity level from each light source.

11. A display system according to claim 9, wherein the light sensing mechanism forms part of the light modulator.

12. A display system according to claim 9, wherein the comparison is determined each time operation of the system is initiated.

13. A display system according to claim 9, wherein the illumination device contains one, and only one, light source.

14. A display system according to claim 9, wherein the illumination device includes a plurality of light sources and wherein said calibration arrangement is designed to establish the input for a desired intensity level for each light source whereby to produce combined light of a desired color.

15. A display system according to claim 14, wherein the particular intensity of light produced by each light source is different.

16. A display system according to claim 14, wherein the desired color is white.

17. A display system according to claim 14, wherein the illumination device consists of red, green and blue light-emitting diodes.

18. A display system according to claim 9, wherein said sensing mechanism is a photodetector.

19. A display system according to claim 9, wherein said sensing mechanism is configured to sense only light within the visible spectrum.

20. A display system according to claim 9, wherein said sensing mechanism is configured to have photopic spectral response substantially similar to the human eye.

22. A display system according to claim 18, wherein the spectral response of said photodetector may vary from photodetector to photodetector and wherein the value representative of the desired intensity level is pre-calibrated to vary proportionally with the photodetector spectral response variation.

23. A display system according to claim 9, wherein said sensing mechanism includes a plurality of photodetectors each configured to sense light of a specific range of wavelengths and wherein each range of wavelengths is different.

10. A display system comprising:

a light modulator;

a separate input-driven illumination device having a plurality of light sources which are adapted to receive variable inputs and which are configured to direct light of variable intensities onto the modulator, depending on said inputs; and

a calibrating arrangement for establishing the inputs for a desired intensity level of said light from each light source, the arrangement including a light sensing mechanism forming part of the light modulator which senses said light from one light source at a time while each light source is driven by an initial input, the calibration arrangement being configured to determine a comparison between the sensed light and a value representative of the desired intensity level of light from the light source, the calibration arrangement further including means responsive to the comparisons for varying the inputs so as to provide light of said desired intensity level from each light source.

21. A method of operating a display system comprising the steps of:

a) providing an input-driven illumination device having one or more light sources which are adapted to receive variable inputs and which are configured to direct light of variable intensities onto a light modulator depending on said inputs;

b) sensing said light from one light source at a time while each light source is driven by an initial input;

c) comparing the sensed light to a value representative of the desired intensity;

d) establishing the inputs for a desired intensity level of said light from each light source in response to the comparisons; and

e) directing the light of said desired intensity level from each light source onto said light modulator.

24. A display system, comprising:

a light modulator;

a separate illumination device including three light sources, each of the three light sources providing light that is substantially in a different color band than two others of the three light sources, each of the three light sources providing an output light intensity related to an input corresponding to that light source; and

a calibrating arrangement that establishes the inputs to the three light sources, the arrangement including a light sensing arrangement that separately senses the output light intensity from each of the three differently-colored light sources and based thereon separately adjusts the input to each of the three differently-colored light sources to achieve a desired output light intensity from each differently-colored light source to achieve a desired color balance in the combination of the light from each of the three differently-colored light sources.

25. A display system, comprising:

a spatial light modulator divided into an array of individually controllable pixels;

a separate light source that provides light to the modulator, the intensity of the light provided being a function of an input signal provided to the light source, wherein said light source has been characterized prior to installation in the display system to determine the magnitude of the input signal that is required to provide a predetermined light intensity, the determined magnitude having been stored as calibration information specific to said particular light source in a memory device associated with the light source;

wherein the calibration information is utilized during operation of the display device to achieve a desired light intensity.

26. A display system as defined in claim 25, wherein there are three such separate light sources, each of the three light sources providing light of a different color.

27. A display system as defined in claim 26, wherein the three light sources are operated in a cyclical, sequential fashion to achieve a perception of white light in the case where the spatial light modulator provides the same degree of modulation for each element of the sequence.

28. A display system as defined in claim 25, wherein the light source is an LED and the light intensity therefrom is a function of the magnitude of the electrical current of the input signal.